Relay replacement silicon gets slew-rate control

Infineon has added slew-rate control to its Hitfet range of relay-replacing low-side switches.

Aimed at automotive and industrial applications, and called Hitfet+, the devices also have enhanced diagnostics, digital status feedback and improved short-circuit robustness.

“Depending on vehicle class, every car produced today has about 7-11 protected low-side power switches,” said Infineon automotive v-p Andreas Doll. “Infineon invented Hitfet protected low-side switches more than two decades ago. Our most recent family will provide switching wherever over-temperature or over-current protection are needed in automotive and industrial applications.”

Controlled slew rate, which is resistor-programmable, has been added to keep transients under control and assist with EMC compliance.

Designed specifically to handle inductive and high-inrush loads, at least 16 ‘+’ versions will eventually be available – from 10 to 800mΩ. So far only the single-channel 3A 50mΩ BTF3050TE for 12V automotive loads is in full production.

While, on the surface, relays look like an easy target for semiconductor replacement, their robustness, power handling and low cost continues to shrug off competition in many applications.

Infineon argument is that the added features make all the difference: diagnosis, digital status feedback, short-circuit protection, and now slew-rate control.

Unlike relays, these Hitfets can be driven with kHz PWM waveforms, allowing valve control solenoids to be operated at 20kHz, and LEDs between 10 and 60W to be dimmed.

Packaging is 5 or 3pin D-PAK or 8pin DSO. Products of one package size are interchangeable, so the same software and PCB layout can address various loads.

Other car uses, proposes the firm, are mid and small-size electric motor drives – for door locks and parking brakes, for example, and also printers, vacuum cleaners, solar power modules, and vending machines.

steve bush

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via Yuichun